Your Ranger/Bronco II is stalling/dieing or
sputtering when hot but runs when it cools off. This can be caused
by a faulty TFI and the biggest culprits are heat. Another culprit
can be a wire grounding out. Problematic TFI's can give off codes
14 (PIP) and 18 (SPOUT).o

The yellow spark output signal wire is
without a section of insulation. This section happens to run through a
shield ground that provided a convenient ground source for the SPOUT
signal. Just the right bump in the road or vibration from the engine
would provide a path of lesser resistance for the SPOUT signal, killing
the coil trigger.

This is where the TFI Modile plugs in to the
distributor to get the PIP signal. Notice the defective
insulation.

Heat Is Your Enemy!:

The top three leads (for PIP signal) can
lose continuity with the back plate (ground) on the module when the unit
is hot. You should consider a remote
mounted TFI. If your TFI is failing from heat, it can
give off computer codes 14 (PIP) and 18 (SPOUT).

General Information

The TFI-IV distributor ignition
system consists of the following components:

Thick
Film Ignition (TFI) modules

Distributor

Camshaft
Position (CMP) sensor

Ignition
coil

The
distributor ignition system designed by Ford has two distinct
configurations. The first configuration is known as the distributor
mounted system, because the TFI is mounted directly on the distributor
housing. The second configuration is known as a remote mount system,
since the TFI is mounted on the engine or front fender apron.

The
distributor used by this system is sealed and houses the CMP sensor. The
distributor does not utilize vacuum or centrifugal advance mechanisms;
the ignition timing is automatically controlled by the Powertrain
Control Module (PCM) and the TFI.

Ford
calls this electronic ignition the Thick Film Integrated-IV (TFI-IV)
ignition system. The TFI module is also known as the Ignition Control
Module (ICM) which reports engine position and rpm to the PCM. The PCM
then determines the proper spark timing and advance, and returns a
reference signal to tell the TFI module to switch the coil, thereby by
creating a spark. The PCM used on these vehicles is referred to by Ford
as the Electronic Engine Control-IV (EEC-IV) module.

System
Operation

The
CMP sensor, housed inside the distributor, responds to a rotating
metallic shutter mounted on the distributor shaft. This rotating shutter
produces a digital Profile Ignition Pick-up (PIP) signal, which is used
by the PCM and TFI to provide base timing information, determine engine
speed (rpm) and crankshaft position. The distributor shaft rotates at
one-half crankshaft speed, therefore the shutter rotates once for every
two crankshaft revolutions.

The
TFI functions in either one of two modes: push start or Computer
Controlled Dwell (CCD). The push start mode allows for increased dwell,
or coil on time, when starting the engine. During this mode, the TFI
determines when to turn on the ignition coil based on engine speed
information. The coil is turned off, thereby firing, whenever a rising
edge of a SPark OUTput (SPOUT) signal is received. The SPOUT signal is
generated by the PCM, and provides spark timing information to the TFI.
During the push start mode, the SPOUT signal only indicates the timing
for coil firing; the falling edge of the SPOUT signal is ignored.
Despite the name, the push start mode is also enabled during engine
starting with the ignition key.

Do
not attempt to push start a vehicle equipped with an automatic
transmission.

The
rotary armature has open areas called windows and tabs called vanes

The
vane interrupts the magnetic field passing through the Hall effect
device

During
the CCD mode, both edges of the SPOUT signal are utilized. The leading
edge of the SPOUT signal is used by the ICM in the same manner as during
the push start mode. The falling edge of the signal is generated to
control the timing for turning the ignition coil on (the TFI no longer
controls this function as during the push start mode). During the CCD
mode, the coil on time, or dwell, is entirely controlled by the PCM
through the SPOUT signal.

In
the event that the SPOUT signal from the PCM is disrupted, the TFI will
use the PIP signal from the CMP to fire the ignition coil, which results
in a fixed spark angle and dwell.

Diagnosis
& Testing

Service
Precautions

Always
turn the key OFF and isolate both ends of a circuit whenever
testing for shorts or continuity.

Never
measure voltage or resistance directly at the processor connector.

Always
disconnect solenoids and switches from the harness before measuring for
continuity, resistance or energizing by way of a 8-volt source.

When
disconnecting connectors, inspect for damaged or pushed-out pins,
corrosion, loose wires, etc. Service if required.

Preliminary
Checks

Visually
inspect the engine compartment to ensure that all vacuum lines and spark
plug wires are properly routed and securely connected.

Examine
all wiring harness and connectors for insulation damage, burned,
overheated, loose or broken conditions. Ensure that the TFI is securely
fastened to the front fender apron.

Be
certain that the battery is fully charged and that all accessories are
OFF during the diagnosis.

Test
Procedures

Perform
the test procedures in the order in which they are presented here.

Ignition
Coil Secondary Voltage Test

Coil
Voltage Test #1 - Crank Mode

1
- Connect
a spark tester between the ignition coil wire and a good engine ground.

2
- Crank
the engine and check for spark at the tester.

3
- Turn
the ignition switch OFF.

4
- If
no spark occurs, check the following:

a.
Inspect the ignition coil for damage or carbon tracking.

b.
Check that the distributor shaft is rotating when the engine is being
cranked.

c.
If the results in Steps a and b are okay, go to Test #4.

5
- If
a spark did occur, check the distributor cap and rotor for damage or
carbon tracking. Go to the Coil Voltage Test #2.

2
- Did the Tach light blink? If No, replace TFI module and check for
spark using the method described in Test #1. If spark was not present,
replace the coil also.

System
Test #7

1
- Disconnect the pin-in-line connector near the TFI.

2
- Crank the engine

3
- Turn the ignition switch OFF.

4
- If a spark did occur, check the PIP and ignition
ground wires for continuity. If okay, the problem is not in the ignition
system.

5
- If no spark occurs, check the voltage at the
positive (+) terminal of the ignition coil with the ignition switch in RUN.

6
- If the reading is not within battery voltage, check
for a worn or damaged ignition switch.

7
- If the reading is within battery voltage, check for
faults in the wiring between the coil and TFI module terminal No. 2 or
any additional wiring or components connected to that circuit.

Spark
Timing Advance Test #8

Spark
timing advance is controlled by the EEC system. This procedure checks
the capability of the ignition module to receive the spark timing
command from the EEC module. The use of a volt/ohmmeter is required.

3
- Start the engine and measure the voltage, at idle,
from the SPOUT connector to the distributor base. The reading should
equal battery voltage.

4
- If the result is okay, the problem lies within the
EEC-IV system.

5
- If the result was not satisfactory, separate the
wiring harness connector from the ignition module. Check for damage,
corrosion or dirt. Service as necessary.

6
- Measure the resistance between terminal No. 1 and
the pin-in-line connector. This test is done at the ignition module
connector only. The reading should be less than 1 ohms.

7
- If the reading is okay, replace the TFI module.

8
- If the result was not satisfactory, service the
wiring between the pin inline connector and the TFI connector.

Our
Old Testing Procedure

STEP
1

Determine if the engine is getting fuel. If injector is fueling chances
are the TFI electronics are ok. If the electronics fail the fuel system
shuts down except for about 20 seconds of start of cranking. If no
fueling or if it quits after 20 seconds of cranking go to step 2.

STEP
2

Check for spark at one of the spark plugs. If spark is found, you may
have a fuel system problem. If spark is not found, check for spark at
the coil wire. If you have spark, you may have a bad rotor, cap, or
wires. If you still have no spark, unplug the harness at the TFI module.
With key off, there should be no voltage present at any terminals of the
harness. With key in the run position there should be voltage at the
"TFI POWER RUN" and the "TACH IDM (COIL NEGATIVE)"
terminals. Pull the small wire off the starter solenoid so engine will
not crank. Have an assistant try to crank the engine. There should be
voltage at "TFI POWER RUN, TFI POWER CRANK (START SIGNAL IN), and TACH IDM
(COIL NEGATIVE)" terminals. If there is not voltages present, there is a possible
wiring problem. If voltages are ok, go to step 3.

STEP
3

With coil wire removed to watch for spark, place ignition key in the run
position. Momentarily touch a jumper wire from "TACH IDM (COIL
NEGATIVE)"
terminal of the harness to a good ground. Spark should jump every time
the jumper is grounded. Do not ground the jumper for more that a couple
of seconds. If no spark is found, make sure that with the key in the run
position there is voltage at one of the coil terminals. If voltage is
present, the coil may be bad, go to step 4. If spark is found, the
problem may be the TFI module or the PIP (profile ignition pickup or
reluctor in the distributor) so go to step 5.

STEP
4

We should now test the coil. Use an ohm meter and probe the resistance
of the two small terminals, and you should find 0.3 to 1.0 ohm. If the
resistance is not ok, it may be a bad coil. If the resistance is ok,
probe one small terminal and the coil wire terminal. Resistance should
be 8000 to 11,500 ohms. If the resistance is not ok, replace coil. If
the resistance is ok, go to step 5.

STEP
5

Testing the pickup coil (PIP) in the distributor is not an easy task,
and best to test the TFI module first, then replace the pickup coil
(PIP) if the TFI module tests ok. I have seen very few pickup coils on
Ford TFI systems go bad. Test the TFI module according to the chart
below. These values may be valid only on an OEM module, but may apply to
aftermarket.